THE QUESTIONS were often better than the answers, but Friday night's presidential debate was useful in framing a contrast between President Bush and Sen. John F. Kerry (D-Mass.). The nominees articulated sharply different positions on health care, the environment, stem cell research and other domestic issues that they had not previously debated. With polls showing their race tightening, the president and his challenger also sharply attacked each other in front of a "town hall" audience of 140 undecided voters. Mr. Bush depicted Mr. Kerry as a tax-hiking liberal too concerned with winning international popularity contests; Mr. Kerry portrayed Mr. Bush as a man who "didn't make the right judgments" and resorted to negative campaigning because of the poverty of his record.

As in the first debate, much of the discussion centered on Iraq, and Mr. Kerry was effective in outlining the president's shortcomings in failing to attract allies or deploy a large enough force. Challenged by his first questioner to justify the invasion in light of evidence that Iraq's weapons capabilities were less advanced than those of many countries, Mr. Bush did little more than repeat, without explanation, that "Saddam Hussein was a unique threat."

But Mr. Bush was effective in pointing out that Mr. Kerry's plan for Iraq is identical to that of Mr. Bush, except for his promise to attract more allies -- unlikely, the president said, because "nobody is going to follow somebody who doesn't believe we can succeed." Mr. Kerry seemed unable to articulate one clear position. "I do believe Saddam Hussein was a threat," he said, but only minutes later he criticized the president for being "preoccupied with Iraq, where there wasn't a threat."

Mr. Bush's criticisms of Mr. Kerry too often amounted to hurling the "liberal" epithet at him rather than engaging him on the merits. "Of course he's going to raise your taxes," Mr. Bush said, though Mr. Kerry promised Friday night that he would not raise taxes on anyone making less than $200,000. Mr. Bush's defense of tax cuts for those wealthiest Americans -- that such cuts will help job-creating small businesses -- is belied by the fact that the overwhelming majority of those filing as small business owners don't pay the top rate. And given his record of fiscal recklessness, on both the spending and tax-cutting sides, the president did not start from a strong position in attacking Mr. Kerry as a big spender. Mr. Bush described himself as a "good steward of the land," but his description did not match his record of opening federal lands to oil and gas exploration, retreating from action on climate change and weakening regulation on clean air.

If Mr. Bush's strategy was to repeat the word "liberal," Mr. Kerry's was to drive home the notion that he had a plan on everything from Iraq to health care to schools to the environment. Like Mr. Bush, he resisted entreaties from moderator Charles Gibson to explain how he would reduce the deficit. Mr. Bush may have had a point when he said that Mr. Kerry's health plan will be more expensive than the Democrat contends, but he was inaccurate in describing Mr. Kerry's plan as typical, liberal "government-sponsored health care."

The candidates left plenty of room for follow-up questions at their third and final debate in Arizona this week, and plenty of topics unexplored. At the top of that list, we'd put the question of the country's fiscal condition even if the next president manages, improbably, to cut the deficit in half in the next several years. The toughest questions, about the looming costs of Social Security and, even more, of Medicare, were left unasked and deserve some rigorous examination this week.

Reprinted from Saturday's late editions